Method for loading and unloading a barge and an equipment for connecting a pusher to a barge

ABSTRACT

A method for loading and unloading a barge ( 40 ), and a mechanism for coupling a pusher ( 30 ) with a barge by means of coupling units ( 10 ) provided on either side of the pusher ( 30 ). To allow loading and unloading of the barge ( 40 ), the pusher is coupled with the barge by means of slides ( 34 ) and vertical guides ( 33 ) comprised in the coupling mechanism, which allow the height position of the barge to change freely in relation to the pusher. After completion of the loading or unloading process, the pushpins ( 11 ) of the coupling units ( 10 ) of the pusher are locked in coupling sockets ( 25 ) or holes in the coupling plates ( 32 ) of the barge.

METHOD OF THE INVENTION

The present invention relates to a method for loading and unloading a barge. According to the method, when the barge is being loaded, the pushpins of the coupling devices of a pushing tug or pusher are inserted into coupling sockets or holes in the coupling plates of the barge at a height corresponding to the current height position of the barge relative to the pusher.

PRIOR ART

In maritime transport, pushers are increasingly used to propel barges. In this way, the hydrodynamics of maritime vessel combinations is improved, their speed is increased and fuel economy improved. Various mechanisms for connecting the barge and the pusher together are known. The principal types of equipment used are the so-called integrated connection or ITB (Integrated Tug and Barge) and the articulated connection ATB (Articulated Tug and Barge) mechanisms. In the case of integrated connection, the pushing vessel is rigidly connected to the barge, in other words, on a rolling sea the pushing vessel moves together with the barge being pushed. In such equipment, the pusher is driven in almost its full length into a deep notch formed in the stem of the barge, which notch is provided with at least three coupling points for rigidly connecting the pusher and the barge together. In an articulated connection, usually only the forward part of the pushing vessel, about 20-35% of the total length of the pusher is driven into a notch formed in the stern of the barge and the pusher is coupled to the barge by means of coupling devices provided on both sides of the pusher. The coupling means comprise pushpins projecting outwards from the sides of the pusher, and the pushpins are move by means of pushpin cylinders in the axial direction so that they can be locked in coupling sockets provided on both sides of the notch in the stem of the barge. The pushpins are provided bearings allowing rotary motion, and they are disposed on the same horizontal transverse axis. The pushpins act as universal shafts about which the pushing vessel can swing longitudinally relative to the barges. The locking position of the pushpin in the locking plate of the barge is selected on the basis of the current relative height positions of the pusher and the barge

Prior-art coupling mechanisms for the coupling of a pusher with a barge involve the problem that it is difficult to change the position of the pushpin of the coupling mechanism of the pusher in the coupling plate of the barge. A need for such an operation appears when the barge is being loaded or unloaded. In this situation, the barge is either sinking deeper or becoming lighter and rising. In prior-art coupling devices, the coupling between pusher and barge has to be released altogether before the vessels can be coupled together again. In this situation, if rough sea conditions prevail, then re-coupling may prove to be impossible and the barge may become adrift. This may result in considerable damage.

OBJECT OF THE INVENTION

The object of the present invention is to achieve a new method for loading and unloading a barge and accomplishing an articulated coupling between the pusher and the barge.

FEATURES OF METHOD OF THE INVENTION

The method of the invention is characterized in that

-   -   the pusher is coupled with the barge by means of slides and         vertical guides comprised in a coupling mechanism to keep the         vessels coupled together during loading and unloading,     -   the height position of the barge is allowed to change freely in         relation to the pusher, and that     -   after completion of the loading or unloading process, the         pushpins of the coupling units of the pusher are locked in         coupling sockets or holes in the coupling plates of the barge.

By applying the method of the invention, the pusher can be easily held so connected to the barge that the pusher and the barge remain reliably coupled together. Yet the coupling permits vertical motion of the barge in relation to the pusher.

MECHANISM OF THE INVENTION

The invention also concerns a mechanism for coupling a pushing tug or pusher with a barge during the loading and unloading of the latter, in which situation the draft of the barge is changing.

PRIOR-ART MECHANISM

In prior-art systems for coupling a pusher and a barge, it is difficult change the position of the pushpin of the coupling device of the pusher in the coupling plate of the barge as the barge is sinking or rising during loading or unloading.

FEATURES OF THE MECHANISM OF THE INVENTION

It is also an object of the present invention to achieve a new articulated coupling mechanism between pusher and barge that does not involve the drawbacks described above. The coupling mechanism of the invention is characterized in that

-   -   the coupling mechanism between the barge and the pusher         comprises slides included in coupling units on either side of         the pusher, and that     -   the coupling plate structures of the barge comprise vertical         guides.

After the height position of the barge has changed due to loading or unloading, the pushpins of the coupling units of the pusher are locked again in coupling sockets or holes in the coupling plates of the barge that correspond to the current relative height positions of the pusher and the barge.

The invention is designed to keep the distance between pusher and barge as short as possible, e.g. 20-25 mm. When this is the case, the torque arm formed by the pushpin and the torque applied to the coupling unit will be small, which means that the forces applied to the hull structures of the pusher can be better anticipated and controlled. Consequently, the coupling units and the associated steel structures can be made substantially lighter than in prior-art devices. As the pushpins of the coupling units have a cylindrical shape, the pushpins need not be pressed against the coupling sockets after the vessels have been coupled together as in the case of prior-art toothed coupling devices.

EMBODIMENTS OF THE MECHANISM OF THE INVENTION A preferred embodiment of the mechanism of the invention is characterized in that

-   -   the slide of the coupling unit of the pusher is included in the         pushpin structure, preferably placed around the pushpin,     -   the slide actuator comprises a hollow shaft surrounding the         pushpin,     -   the vertical guide in the coupling plate of the barge is in         alignment with the coupling sockets.

This arrangement allows the pushpin to be moved directly through the slide to lock it in a coupling socket at a suitable height in the bottom of the guide slot.

Another preferred embodiment of the mechanism of the invention is characterized in that

-   -   the slide in the coupling unit is connected to its actuator,         such as a hollow shaft, via a ball and socket joint that allows         the slide to turn and rotate freely depending on how the barge         is moving in relation to the pusher.

A third preferred embodiment of the mechanism of the invention is characterized in that

-   -   the slide actuator and/or the pushpin of the coupling unit         are/is connected to a hydraulic circuit of the mechanism that         comprises a hydraulic lock for hydraulically locking the slide         actuator and/or the pushpin in a locked position.

A fourth preferred embodiment of the mechanism of the invention is characterized in that

-   -   the coupling unit comprises a pneumatic cylinder included in the         pushpin structure, preferably placed inside the pushpin, for         accomplishing pneumatic spring action of the pushpin during the         coupling process.

The movements of the pushpins according to the invention are preferably accomplished using both pneumatic and hydraulic techniques. In the actuating cylinders inside the pushpin, compressed air is used as an elastic medium to achieve a spring action of the pushpin. The pushpin is locked by means of a hydraulic cylinder. In addition, the coupling unit mounted in the pusher comprises a hydraulic operating unit for actuating the hydraulic cylinder, a hydraulic pressure accumulator and control units. The compressed air needed by the coupling unit is preferably obtained from the pusher's own pneumatic network. Mounted on the steel structures of the barge is a coupling plate, such as a socket plate for the coupling of the pushpin, to which plate the pushpins can be coupled and locked in a coupling socket or hole at a suitable height.

Comprised in the pushpin structure is a slide, which can be pressed against a vertical guide slot in the coupling plate of the barge. When the slide of the pusher has been pressed into the guide of the barge, the pushpin can be released from the coupling socket without the pusher being detached from the barge. In this situation, the pusher is coupled to the barge via a vertical guide on the barge so that the pusher and the barge can move freely in relation to each other only in a vertical direction. Thus, the barge can be safely loaded or unloaded. The change in vertical position of the barge relative to the pusher is fully controlled. After the loading or unloading has been finished, the pushpin of the pusher is locked in that coupling socket in the coupling plate of the barge that is currently aligned with the pushpin at the same height.

In the following, the invention will be described by the aid of examples with reference to the attached drawings, wherein

FIG. 1 presents a diagrammatic top view of a pusher and a barge as a horizontal section in a situation where the vessels have not yet been coupled together, and coupling elements used to connect a pushing vessel to a barge.

FIG. 2 presents the pusher and barge of FIG. 1 at an initial stage of an operation of coupling the vessels together,

FIG. 3 presents a diagrammatic top view of the pusher and barge of FIG. 1 when coupled together.

FIG. 4 presents a side view of a coupling plate attached to the side of a barge.

FIG. 5 presents a sectional view of the coupling unit of a pusher.

FIG. 6 presents a sectional top view of the coupling unit of a pusher presented in FIG. 5 and the coupling plate of a barge at the initial stage of a coupling operation.

FIG. 7 presents the coupling unit of FIG. 5 engaged in the coupling plate of the barge.

FIG. 8 presents the coupling unit of FIG. 5 at the initial stage of disengagement from the barge.

FIG. 9 presents the coupling unit of FIG. 5 when completely disengaged from the barge.

FIG. 10 presents a side view of a part of a coupling plate to be mounted on the side of a barge according to a second embodiment.

FIG. 11 presents a section taken from FIG. 10 along line XI-XI.

FIG. 12 corresponds to FIG. 4 and presents a coupling plate to be mounted on the side of a barge and a part of the coupling unit of a pusher in diagrammatic view according to a second embodiment.

FIG. 13 presents a sectional top view of the coupling unit of a pusher and the coupling plate of a barge at the initial stage of a coupling process.

FIG. 14-20 correspond to FIG. 13 and illustrate different stages of a coupling process.

FIG. 21 corresponds to FIG. 17 and presents the coupling unit of a pusher when locked in the coupling plate of a barge and a diagrammatic view of a hydraulic lock of the coupling unit.

FIG. 22 presents a part of the coupling unit of FIG. 7 and the end of the pushpin according to a third embodiment.

FIG. 23 corresponds to FIG. 22 and presents the pushpin of the coupling unit in another position.

FIG. 1 presents the bow of a pusher 30 and the stern of a barge 40 with a notch 42 for the bow of the pusher 30. Mounted on the sides of the stern notch 42 of the barge 40 are coupling plates 32 a and 32 b (reference numbers added to FIG. 1), which comprise coupling plates 23 a and 23 b as well as guide plates 24 a and 24 b attached to them. When the pusher 30 is to be connected to the barge 40, the bow of the tug 30 is advanced into the stern notch 42 of the barge 40, whereupon the pushpins 11 a and 11 b comprised in the coupling units 10 a and 10 b of the pusher 30 engage the sockets 25 a and 25 b in the socket plates 23 a and 23 b of the barge 40 as described in connection with the following figures.

FIG. 2 illustrates a situation where the bow of the pusher 30 is advancing into the notch 42 in the stern of the barge 40. To permit coupling between the pusher 30 and the barge 40, the pushpins 11 a and 11 b of the coupling units 10 a and 10 b mounted in the side structures 31 of the pusher 30 are in a protruded position. At the initial phase of the coupling process illustrated in FIG. 2, the pushpins 11 a and 11 b are leaning on the guide plates 24 a and 24 b attached to the side structures 41 of the barge 40. The guide plates 24 a and 24 b are provided with wedge-shaped recesses for guiding the pushpins 11 a and 11 b into the sockets 25 a and 25 b in the socket plates 23 a and 23 b as the pusher 30 is moving further into the notch 42 of the barge 40.

From FIG. 2 it can be seen that the guide plates 24 a and 24 b form wedge-shaped surfaces against which the pushpins 11 a and 11 b lean. Thus, the pushpins 11 a and 11 b are pushed into the narrowing passage by the guide plates 24 a and 24 b. According to the invention, this is possible because in the coupling units 10 a and 10 b the pushpins 11 a and 11 b are pressed against the guide plates 24 a and 24 b by means of pneumatic cylinders. In this situation, the compressed air functions as a kind of spring so that the pushpins 11 a and 11 b can move axially during the coupling process. This arrangement provides the advantage that the pushpins 11 a and 11 b are elastically pressed against the guide plates 24 a and 24 b, so that there is no harmful clearance between the pusher 30 and the barge 40 in the coupling situation.

In FIG. 3, the articulated coupling between the pusher 30 and the barge 40 has been locked. After the bow of the pusher 30 has moved into the notch 42 in the stern of the barge 40, the pushpins 11 a and 11 b of the coupling units 10 a and 10 b, located on the same geometric axis, have latched into the coupling sockets in the socket plates 23 a and 23 b comprised in the coupling plates 32 a and 32 b attached to the side structure 41 of the barge 40. The locking is implemented using a hydraulic cylinder provided in connection with the pushpin 11. The hydraulic cylinder produces a substantially larger locking force than the pneumatic cylinder, which is used in the invention only for moving the locking pin and as a pneumatic spring element. After this, the pushpin 11 is locked in the coupling socket by a hydraulic locking system, which will be described below.

FIG. 4 presents a coupling plate 32 attached to the side structure 41 of the barge, which comprises a socket plate 23 and a guide plate 24 attached to it. As can be seen from the figure, the socket plate 23 comprises a number of coupling sockets 25 at different heights, and in alignment with each coupling socket there is also a wedge-shaped guide slot of the guide plate 24 for guiding the pushpin of the pusher into the coupling socket 25 of the socket plate 23. The socket plate 23 is provided with several coupling sockets 25 to allow the pusher to be coupled with the barge regardless of the draft of the barge, which depends on its load.

FIG. 5 presents a coupling unit 10 mounted in the side structures 31 of the pusher. It comprises a pushpin 11 movable in a pushpin cylinder 12. The pushpin 11 is movably mounted inside the liner of the pushpin cylinder 12 by means of bearing bushes 13 and 14. The bearing bushes 13 and 14 are so designed that they can withstand the large transverse or radial forces applied to the pushpin in rough sea conditions and the large torques resulting from such forces. The pushpin 11 is locked by means of the piston 18 of the hydraulic cylinder 17. However, the hydraulic piston 18 is not connected to the pushpin 11 directly but via a pneumatic cylinder 26 and a pneumatic piston 15 provided inside the pushpin 11.

The hydraulic piston 18 and the pneumatic piston 15 are interconnected by a connecting rod 16. The joint action of the hydraulic cylinder 17 and the pneumatic cylinder 26 produces the effect that, at the coupling phase when the hydraulic piston 18 has not yet been pushed to its extreme position toward the pushpin 11, the pneumatic cylinder 26 and the pneumatic piston 15 constitute a pneumatic spring for pressing the pushpin 11 against the wedge-shaped guide plate attached to the side structure of the barge. It is only after the pushpin 11 has penetrated into the coupling socket in the socket plate of the barge that the hydraulic piston 18 of the hydraulic cylinder 17 of the coupling unit 10 is pushed to its extreme position towards the pushpin 11, with the result that the pushpin 11 is latched into position and held immovable by a great hydraulic pressure, which is e.g. 80-140 bar.

FIG. 5 visualizes this locked situation with both the hydraulic piston 18 and the pneumatic piston 15 in their extreme positions on the right in the figure. In this situation, the elastic capacity of the pneumatic cylinder 26 has been exhausted and the pushpin 11 is solidly locked in position by the mechanical elements. The coupling unit 10 in FIG. 5 also comprises a piston rod 19 connected to the hydraulic piston 18, with a piston position indicator rod 20 attached to the piston rod. Placed at the end of the position indicator rod 20 is a bracket 27 whose position indicates the position of the pistons 15 and 18. The position of the hydraulic piston 18 and the pneumatic piston 15 is indicated and controlled using limit switches 28 as presented in the following figures.

FIG. 6 presents the coupling unit 10 mounted in the side structure 31 of the pusher, with the pushpin 11 about to be latched into the socket plate 23 of the coupling plate 32 attached to the side structure of the barge. In this figure, the hydraulic piston 18 in the hydraulic cylinder 17 of the coupling unit 10 is approximately in its middle position in the hydraulic cylinder 17. This piston position is accomplished by means the control system of the hydraulics by using position indication data produced by a first limit switch 28 a. At the same time, compressed air is supplied into the pneumatic cylinder 26 inside the pushpin 11, into the space to the right of the pneumatic piston 15 in FIG. 6, with the result that the pushpin 11 is thrust out to its extreme position.

In FIG. 6, the protruded pushpin 11 is leaning on the guide plate 24 attached to the side structure of the barge. As the pusher advances into the notch in the stern of the barge, the pushpin 11 is pressed against the wedge-shaped guide plate 24. However, the pushpin 11 pressed against the wedge-shaped guide plate 24 is able to move inwards as the air in the pneumatic cylinder 26 is compressed, thus acting as a pneumatic spring. There is no unnecessary play in the coupling process, so the coupling action is a continuously controlled process.

FIG. 7 illustrates a situation where the hydraulic piston 18 of the coupling unit 10 has been moved to the right in FIG. 7 to its extreme position, to a position indicated by a second limit switch 28 b. The pushpin 11 has now been locked in the coupling socket 25 in the socket plate 23 of the coupling plate 32. At the same time, the pneumatic piston 15 in the pneumatic cylinder 26 is in its extreme position on the right so that the pushpin 11 is in a locked state without any elastic capacity. The coupling between the pusher and the barge remains in this position all the time during the sea transport. For possible abrasion taking place in the locking elements, the coupling unit 10 is additionally provided with a wearing plate 21 to prevent the socket plate 23 from being frayed against the side structure 31 of the pusher.

As shown in FIG. 7, the pushpin 11 has a shoulder near its end, said shoulder forming the frontal face 29 leaning against the socket plate 23. As the frontal faces 29 are firmly pressed against the socket plates 23 on both sides of the pusher, no harmful lateral play appears between the pusher and the barge. However, a small clearance is left between the wearing plate 21 and the socket plate 23 on either side of the pusher. Using the centralizing control hydraulics comprised in the coupling unit 10, the pusher is kept centrally positioned in the notch in the stem of the barge as far as possible to maintain equal lateral clearances on both sides.

FIG. 8 illustrates a situation where the coupling unit 10 of the pusher is being disengaged from the coupling plate 32 of the barge. The hydraulic piston 18 of the coupling unit 10 has been retracted to the left to a position indicated by a third limit switch 28 c. At the same time, the pneumatic cylinder 26, i.e. the cylinder space to the right of the pneumatic piston 15 in FIG. 8, is depressurized. The end of the pushpin 11 now remains supported by the guide plates 24. When the pusher is reversed in this situation, the coupling unit 10 will be released without a crash even if the mass centers of the coupled vessels should have changed during towage.

FIG. 9 illustrates a situation where the pusher has been completely disengaged from the barge. The pushpin 11 of the coupling unit 10 has been completely retracted into the pushpin cylinder 12 by moving the hydraulic piston 18 to its extreme position on the left in FIG. 9, a position indicated by a fourth limit switch 28 b. At the same time, in the pneumatic cylinder 26, compressed air is supplied to the left-hand side of the pneumatic piston 15 as seen in FIG. 9. In this way, the pushpin 11 is moved to its extreme position on the left in FIG. 9. In this position, the end of the pushpin 11 of the coupling unit 10 does not protrude outside the side structure 31 of the pusher, so the pusher can be used for other purposes, e.g. for towing operations, in which the coupling unit 10 is not needed.

FIG. 10 presents a sub-element of the coupling plate 32 implemented according to a second embodiment of the invention. It comprises a socket plate 23 preferably made of cast steel and provided with a coupling socket 25, and a guide plate 24 preferably made by welding from sheet steel and having a wedge-shaped guide slot. A number of sub-elements as presented in FIG. 10 are mounted on the side of the barge, said elements together forming a coupling plate 32 as shown in FIG. 12, which comprises several coupling sockets 25 and guide plates 24 placed one above the other. The pushpin 11 of the coupling unit 10 of the pusher 30 is pressed against the surface of the guide plate 24 and is guided by the wedge-shaped guide slot and then locked in that coupling socket 25 of the socket plate 23 which corresponds to the prevailing height position of the barge 40 relative to the pusher 30.

However, the height position of the barge 40 may change. Such a situation arises e.g. when the barge 40 is being loaded, causing it to be sink deeper, or when it is being unloaded, in which case its weight is reduced and the barge rises. When the height position of the barge 40 changes, the pushpin 11 of the coupling unit 10 has to be released from the coupling socket 25 and moved into another coupling socket 25 that corresponds better to the changed height position of the barge 40 relative to the pusher 30.

In prior-art coupling equipment, releasing the pushpin 11 from the coupling socket 25 of the coupling plate 32 means that the barge 40 is completely disengaged from the pusher 30. It is obvious that in rough sea conditions this operation cannot be undertaken at all, because in that case the pusher 30 and barge 40 detached from each other would dangerously bump against each other and it would be impossible to couple them together again.

To eliminate the above-mentioned problem, the coupling plate 32 mounted on the barge 40 in this embodiment is provided with a recess 33 that functions as a vertical guide. The coupling unit 10 of the pusher 30 comprises a corresponding slide leans against this vertical guide. This provides the advantage that, when the pushpin 11 of the coupling unit of the pusher 30 is released from the coupling socket 35 of the coupling plate 32 on the barge 40, the barge 40 is not completely disengaged from the pusher 30. As the slide of the coupling unit is pressed against the recess 33 in the coupling plate 32, it still keeps the barge 40 coupled to the pusher 30. In this situation, the vessels can still move vertically in a controlled manner relative to each other so that the pushpin can always be locked in the coupling socket 25 that is best suited to the current height position of the barge 40.

FIG. 11 presents a cross-sectional view of the coupling plate 32 in FIG. 10. In the coupling situation, the pushpin 11 of the coupling unit 10 is pressed against the surface of the guide plate 24 and moves in the wedge-shaped guide slot into the coupling socket 25 in the socket plate 23, the pusher 30 being thus locked to the barge 40. When the pushpin 11 has to be moved into another coupling socket 25, then it is retracted and released from the coupling socket 25. However, the slide pressed against the guide surface of the recess 33 still keeps the pusher 30 and barge 40 coupled together. The slide prevents relative lateral motion between these vessels while allowing their vertical movements. If the weight of the barge 40 has been reduced e.g. due to the unloading of cargo, then the barge 40 and the pusher 30 will freely assume a new height position relative to each other. After that, the pushpin 11 is locked in the coupling socket 25 corresponding to this situation.

FIG. 12 presents a coupling plate 32 composed from sub-elements as shown in FIGS. 10 and 11, designed to be mounted on the side of a barge 40. It comprises coupling sockets 25 with a guide plate 24 aligned with each socket. This embodiment of the coupling plate 32 has a recess 33 in the area of the coupling sockets 25, said recess functioning as a vertical guide. In addition to the coupling plate 32, to visualize the action of the coupling unit, FIG. 12 also shows diagrammatically how the main parts of the coupling unit of the pusher 30 are disposed in relation to the coupling plate 32 on the barge 40.

In FIG. 12, the pushpin 11 of the coupling unit of the pusher 30 is in a position opposite to a coupling socket 25 of the coupling plate 32. In this situation, the pushpin 11 may be either in a position locked to this coupling socket 25 or it may be in a released position. The pushpin is released e.g. when the weight of the barge 40 has been reduced due to unloading or when its weight is increased during loading. In the situation where the pushpin 11 is released, the pusher 30 and the barge 40 only remain coupled together via the coupling plate 32 of the barge 40 and the slide 34 of the coupling unit of the pusher 30, the slide being able to move vertically in the guide 33. The slide 34 is pressed against the guide 33 by means of a hollow shaft 35 surrounding the pushpin 11. The slide 34 and the hollow shaft 35 are connected by a ball joint that allows the slide 34 to be both turned and rotated in relation to the shaft. Therefore, these elements also function as an axis between pusher and barge as the pusher is swinging longitudinally in relation to the barge. After the barge 40 has assumed a new height position after being loaded or unloaded, the pushpin 11 is locked to another coupling socket 25, i.e. in the socket that lies at the level of the pushpin 11 at that stage.

FIG. 13 presents a coupling unit 10 according to another embodiment, mounted in the side structures of a pusher 30, said unit comprising a pushpin 11 and a slide 34 moved by means of a hollow shaft 35 fitted around the pushpin 11. The slide 34 and the hollow shaft 35 are connected by spherical surfaces 36 fitted against each other, allowing the slide 34 to move freely into the right position, i.e. to be inclined in any direction and also to rotate when the slide 11 is being pushed or has been pushed against the guide 33 in the coupling plate 32 of the barge 40 by a hydraulic system, which is indicated in FIG. 13 in general form by reference number 52.

In FIG. 13, the pushpin 11 of the coupling unit 10 of the pusher 30 is shown in a situation where the pushpin remains pressed against a wedge-shaped guide plate 24 in the coupling plate 32 on the barge. In the coupling situation illustrated in FIG. 13, the pusher and its coupling unit 10 are moving so that the pushpin 11 advances towards a coupling socket 25 in the coupling plate 32. Compressed air is supplied into the pneumatic cylinder 26 via the piston 15, piston rod 16 and pneumatic hoses 37. The pneumatic source is not shown in the figure, but preferably it is the pusher's own pneumatic network. The position of the piston 15 is indicated and controlled using a position indicator 20 and limit switches 28. In FIG. 13, the position indicator 20 is located directly opposite to the first limit switch 28 a.

In FIG. 14, the pusher and the coupling unit 10 have already advanced to a position where the pushpin 11 is being locked to the coupling socket 25 in the coupling plate 32 of the barge 40. It can be seen from the figure that the hydraulic circuits HYDR1 and HYDR2 have not yet been activated as the piston 15 of the pneumatic cylinder 26 is still stationary with the position indicator 20 located at the first limit switch 28 a. However, the pushpin 11 has been pressed slightly inwards towards the piston 15 of the pneumatic cylinder 26. Thus, the compressed air in the cylinder 26 functions as a sort of spring which can be used to apply to the pushpin 11 an orifice pressure directed against the coupling plate 32.

In FIG. 15, the compressed air in the cylinder 26 has pressed the pushpin 11 into the coupling socket 25 in the coupling plate 32 of the barge 40 and at the same time the pushpin 11 has moved in the pneumatic cylinder 26 to the bottom of the socket. In this situation, the coupling between the pusher 30 and the barge 40 is only held locked by the pneumatically loaded pushpin 11.

In FIG. 16, the slide 35 of the coupling unit 10 has been pressed into the guide 33 in the coupling plate 32 of the barge 40. Thus, both coupling elements, both the pushpin 11 and the slide 35 are in the locking position. The movement of the slide 35 into the locking position is accomplished by means of hydraulic circuit HYDR2 comprised in the hydraulic system 52, the force being transmitted via piston 39 in hydraulic cylinder 38.

In FIG. 17, the piston 18 in hydraulic cylinder 17 in the coupling unit 10 has been moved by means of hydraulic circuit HYDR2 comprised in the hydraulic equipment to its extreme position on the right as seen in the figure, in which position the piston 15 connected to it via piston rod 16 locks the pushpin 11 in position in the coupling socket 25 in the coupling plate 32. The position indicator 20 is now at the second limit switch 28 b, indicating that the coupling unit 10 of the pusher 30 is hydraulically locked to a coupling socket in the coupling plate 32 of the barge 40.

FIG. 18 illustrates a situation where the piston 18 in hydraulic cylinder 17 has been moved by means of hydraulic circuit HYDR1 comprised in the hydraulic equipment 52 to its extreme position on the left as seen in the figure. In this case, the piston 15 connected via piston rod 16 to piston 18 also moves the pushpin 11 to the left in the figure. In this way, the pushpin 11 is drawn out of the coupling socket 25, thereby releasing the coupling between the pusher 30 and the barge 40 from its locked state. The position indicator 20 is now at the third limit switch 28 c. However, the coupling still remains locked in the lateral direction because the slide 34 of the coupling unit 10 remains in the guide 33 in the coupling plate 32, so that the slide 34 can only move in the vertical direction. This coupling mode is used when the barge is being loaded or unloaded, in which situation its height position relative to the pusher is changing.

FIG. 19 illustrates a situation where the pusher 30 is being disengaged from the barge 40. By means of hydraulic circuit HYDR2 comprised in the hydraulic equipment 52, the hollow shaft 35 and the slide 34 are moved to the left as seen in the figure, with the result that the slide 34 is released from the guide 33 in the coupling plate 32. At the same time, the pushpin 11 is also moved somewhat to the right in the figure by means of hydraulic piston 18 and pneumatic cylinder 16. The position indicator 20 is now at the fourth limit switch 28 d.

FIG. 20 illustrates a situation where the pusher 30 and the barge 40 are disengaged from each other. The pistons 18 and 39 in either hydraulic circuit HYDR1 and HYDR2 are now in their extreme positions on the left as seen in FIG. 20, in which situation the pushpin 11 and the slide 34 are also in a retracted position in the coupling unit 10 of the pusher 30. The position indicator 20 is now also in its extreme position on the left as seen in the figure, at the fifth limit switch 28 e.

FIG. 21 is a diagrammatic representation of hydraulic circuit HYDR1 comprised in the hydraulic equipment 52 of the coupling unit 10, said circuit being indicated by reference number 43 in FIG. 21. This hydraulic circuit operates hydraulic cylinder 17 and its piston 18 and also functions as a hydraulic lock for locking the pushpin 11 in the locked position shown in FIG. 21. The hydraulic circuit comprises an electromagnetically controlled valve 44 used to control the flow of hydraulic liquid from a hydraulic pump P into the cylinder, to the desired side of the piston 18, as well as the flow from the opposite side of the piston 18 back into a tank T. In addition, the hydraulic circuit 43 comprises a check valve 45 and a controllable pressure relief valve 46.

When the piston 18 is actuated by the hydraulic circuit 43, the pressure relief valve 46 permits the flow of hydraulic liquid at a normal operating pressure, but when the hydraulic circuit 43 functions as a hydraulic lock, the pressure setting for the pressure relief valve 46 is so high that the flow of hydraulic liquid is practically stopped. In this situation, the pushpin 11 is hydraulically locked to its locking position in a coupling socket in the coupling plate 32 of the barge as shown in FIG. 21. By means of the pressure relief valve 46, it is possible to control the locking pressure and the corresponding locking force by which the pushpin is allowed to be pushed into the socket. The locking force of the pushpin may therefore be considerably greater than the force needed for actuating the pushpin.

A hydraulic lock like the one presented in FIG. 21 may also be included in the second hydraulic circuit HYDR2 connected to cylinder 38, to be used for locking the slide 34 of the coupling unit 10 to the guide slot 33 in the coupling plate 32 of the barge.

FIG. 22 presents a coupling unit 10 having a pushpin 11 designed to withstand very high torsional moments. The stem 50 of the pushpin 11 inside the bearing bush 13 of the cylinder 12 has therefore a considerably larger diameter than the pushpin 11 end to be fitted into the socket plate 23. From the sectional view in FIG. 22, it can be seen that between the narrower end and the wider stem 50 of the pushpin 11 there is a curved part forming a smooth junction with the shoulder 29 at the end of the stem 50. Attached to the end face of the shoulder 29 is a stopper disk 51, which also holds a sealing gasket 48 in position on the stem.

In the situation illustrated by FIG. 22, when the end of the pushpin 11 has been pushed into a coupling socket 25 in the socket plate 23, the hard plated stopper disk 51 attached to the shoulder 29 forms the end face of the pushpin 11 and is pressed against the socket plate 23 in the locked position. Naturally the two pushpins 11 provided on either side of the pusher are pressed simultaneously against the respective socket plates of the barge. As both pushpins 11 are connected to the same hydraulic system, the pusher can be centered with respect to the barge by moving the pushpins 11.

The coupling unit 10 in FIG. 22 is particularly durable because the pushpin 11 end to be locked in the coupling socket 25 of the socket plate 23 and the stem 50 of the pushpin 11 are clearly differentiated from each other and the stem 50 can withstand large lateral and torsional forces as it has a large diameter. Since the pushpin end which is chafed against the socket plate 23 and may be battered during the coupling process is completely separated from stem 50, the outer surface of the stem 50 adjacent to the bearing bush 13 can not be damaged.

Further, in the structure of the coupling unit 10 presented in FIG. 22, the shoulder 29 of the pushpin 11 can be provided with a hard-plated annular stopper disk 51, which effectively functions as a kind of thrust bearing between the pushpin and the socket plate. Therefore, the pushpins 11 have a good resistance to the forces resulting from the centering and hydraulic locking of the pushpins 11 by the hydraulic system.

Another advantageous feature of the coupling unit structure 10 presented in FIG. 22 is that the outer end of the bearing bush 13 of the cylinder 12 is provided with a sealing gasket 47 and likewise the end of the stem 50 of the pushpin 11 is provided with a sealing gasket 48 fitted at the shoulder 29, which gaskets together prevent oil leakage in all positions of the pushpin 11.

FIG. 23 presents the coupling unit 10 of FIG. 22 with the pushpin 11 in another position. The pushpin 11 in the coupling unit 10 is now in a retracted position inside the bearing bush 13 of the cylinder 12. It can be seen from FIG. 23 that the sealing gasket 48 fitted on the shoulder 29 at the end of the stem 50 of the pushpin 11 effectively prevents oil leakage through the gap between the stem 50 of the pushpin 11 and the bearing 13 of the cylinder 12.

LIST OF REFERENCE NUMBERS

-   10 coupling unit -   11 pushpin -   12 pushpin cylinder -   13 bearing bush (for pushpin) -   14 bearing bush -   15 pneumatic piston -   16 piston rod (connecting the pistons) -   17 hydraulic cylinder -   18 hydraulic piston -   19 piston rod (for position indicator) -   20 position indicator rod -   21 wearing plate -   22 limit switch -   23 socket plate -   24 guide plate -   25 coupling socket -   26 pneumatic cylinder -   27 bracket -   28 limit switch -   29 end face of shoulder -   30 pusher, pusher tug -   31 side structure -   32 coupling plate, -   33 vertical guide slot -   34 slide -   35 hollow shaft, outer shaft -   36 spherical surface -   37 pneumatic hose -   38 hydraulic cylinder -   39 hydraulic piston -   40 barge -   41 side structure -   42 notch -   43 hydraulic lock -   44 solenoid valve -   45 check valve -   46 pressure release valve -   47 sealing gasket -   48 sealing gasket -   49 bearing (of hollow shaft) -   50 stem of pushpin -   51 annular bearing disk on the end face (gasket retaining ring) -   52 hydraulic equipment 

1. A method for loading and unloading a barge (40), according to the method, when the barge is being loaded, the pushpins (11) of the coupling devices (10) of a pushing tug or pusher (30) are inserted into coupling sockets (25) or holes in the coupling plates (32) of the barge at a height corresponding to the current height position of the barge relative to the pusher, characterized in that the pusher (30) is coupled with the barge (40) by means of slides (34) and vertical guides (33) comprised in a coupling mechanism to keep the vessels coupled together during loading and unloading, the height position of the barge (40) is allowed to change freely in relation to the pusher (30), and that after completion of the loading or unloading process, the pushpins (11) of the coupling units (10) of the pusher (30) are locked in coupling sockets (25) or holes in the coupling plates (32) of the barge (40).
 2. A mechanism for coupling a pushing tug or pusher (30) with a barge (40) during the loading and unloading of the latter, in which situation the draft of the barge is changing, characterized in that the coupling mechanism between the barge (40) and the pusher (30) comprises slides (34) included in coupling units (10) on either side of the pusher, and that the coupling plate (32) structures of the barge (40) comprise vertical guides (33).
 3. A mechanism as claimed in claim 2, characterized in that the slide of the coupling unit (10) of the pusher (30) is included in the pushpin (11) structure, preferably placed around the pushpin, the slide (34) actuator comprises a hollow shaft (35) surrounding the pushpin (11), the vertical guide (33) in the coupling plate (32) of the barge (40) is in alignment with the coupling sockets (25). 4-6. (canceled)
 7. A mechanism as claimed in claim 2, characterized in that the slide (34) in the coupling unit (10) is connected to its actuator, such as a hollow shaft (35), via a ball and socket joint (36) that allows the slide to turn and rotate freely depending on how the barge (40) is moving in relation to the pusher (30).
 8. A mechanism as claimed in claim 3, characterized in that the slide (34) in the coupling unit (10) is connected to its actuator, such as a hollow shaft (35), via a ball and socket joint (36) that allows the slide to turn and rotate freely depending on how the barge (40) is moving in relation to the pusher (30).
 9. A mechanism as claimed in claim 2, characterized in that the slide (34) actuator and/or the pushpin (11) of the coupling unit (10) are/is connected to a hydraulic circuit (52) of the mechanism that comprises a hydraulic lock (43) for hydraulically locking the slide (34) actuator and/or the pushpin in a locked position.
 10. A mechanism as claimed in claim 3, characterized in that the slide (34) actuator and/or the pushpin (11) of the coupling unit (10) are/is connected to a hydraulic circuit (52) of the mechanism that comprises a hydraulic lock (43) for hydraulically locking the slide (34) actuator and/or the pushpin in a locked position.
 11. A mechanism as claimed in claim 7, characterized in that the slide (34) actuator and/or the pushpin (11) of the coupling unit (10) are/is connected to a hydraulic circuit (52) of the mechanism that comprises a hydraulic lock (43) for hydraulically locking the slide (34) actuator and/or the pushpin in a locked position.
 12. A mechanism as claimed in claim 8, characterized in that the slide (34) actuator and/or the pushpin (11) of the coupling unit (10) are/is connected to a hydraulic circuit (52) of the mechanism that comprises a hydraulic lock (43) for hydraulically locking the slide (34) actuator and/or the pushpin in a locked position.
 13. A mechanism as claimed in claim 2, characterized in that the coupling unit (10) comprises a pneumatic cylinder (26) included in the pushpin (11) structure, preferably placed inside the pushpin, for accomplishing pneumatic spring action of the pushpin during the coupling process.
 14. A mechanism as claimed in claim 3, characterized in that the coupling unit (10) comprises a pneumatic cylinder (26) included in the pushpin (11) structure, preferably placed inside the pushpin, for accomplishing pneumatic spring action of the pushpin during the coupling process.
 15. A mechanism as claimed in claim 7, characterized in that the coupling unit (10) comprises a pneumatic cylinder (26) included in the pushpin (11) structure, preferably placed inside the pushpin, for accomplishing pneumatic spring action of the pushpin during the coupling process.
 16. A mechanism as claimed in claim 8, characterized in that the coupling unit (10) comprises a pneumatic cylinder (26) included in the pushpin (11) structure, preferably placed inside the pushpin, for accomplishing pneumatic spring action of the pushpin during the coupling process.
 17. A mechanism as claimed in claim 9, characterized in that the coupling unit (10) comprises a pneumatic cylinder (26) included in the pushpin (11) structure, preferably placed inside the pushpin, for accomplishing pneumatic spring action of the pushpin during the coupling process.
 18. A mechanism as claimed in claim 10, characterized in that the coupling unit (10) comprises a pneumatic cylinder (26) included in the pushpin (11) structure, preferably placed inside the pushpin, for accomplishing pneumatic spring action of the pushpin during the coupling process.
 19. A mechanism as claimed in claim 11, characterized in that the coupling unit (10) comprises a pneumatic cylinder (26) included in the pushpin (11) structure, preferably placed inside the pushpin, for accomplishing pneumatic spring action of the pushpin during the coupling process.
 20. A mechanism as claimed in claim 12, characterized in that the coupling unit (10) comprises a pneumatic cylinder (26) included in the pushpin (11) structure, preferably placed inside the pushpin, for accomplishing pneumatic spring action of the pushpin during the coupling process. 